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The earth is approximately ___% the size of the sun.
_____ is the source of energy that drives the Earth's climate system.
______ from the sun travels through the vacuum of space, passes through the Earth's atmosphere and is absorbed by the surface
Radiation from the sun is measured in
Watts per meter squared (W/m2)
The sun-warmed surface of the earth transfers energy to the atmosphere WHICH CREATES
The amount of energy received varies across the globe depending on
3 earth - sun relationships
All things above absolute zero emit
Electromagnetic energy / radiation due to their vibrating molecules.
Radiation is a form of _____ energy
The only way energy can travel through the vacuum of space is
The electromagnetic spectrum spans from measurements in
Kilometers to nanometers
All EMR travels at this speed
The speed of light
The amount of energy contained within specific radiation is determined by
Shorter EMR wavelength =
Longer EMR =
2 Radiation Laws
Stefan Boltzmann Law & Wien's Law
Stefan Boltzmann Law
The total energy emitted by an object depends on it's temperature. Hotter objects emit more energy than cooler objects.
Energy = a constant X temp in K to the 4th power
The wavelength emitted depends on an object's temperature. Hotter objects radiate at shorter wavelengths than cooler objects.
Wavelength = constant / temp of object.
Since we know the sun is hotter than the earth, we can conclude that
The sun emits much more radiation than the earth & the sun emits EMR in much shorter wavelength .
The position of the earth relative to the sun effects energy in these ways
The timing, intensity, and location of incoming energy.
3 important Earth-Sun relationships
The earth rotates on it's axis
The earth revolves around / orbits the sun
The earth tilts on it's axis
Earth's rotation on it's axis causes
Diurnal Cycle of Day and Night
Which affects temperature, shadows, & light
Revolution / orbit of the earth around the sun creates
Year length 365.25 days
This orbit is slightly elliptical / not truly circular
The elliptical rotation causes
The earth is not always the same distance from the sun. It varies by 5 million km which causes a 6% difference in energy.
When the sun and earth are closest (January)
When the sun and earth are furthest apart (July)
Axial Orientation / Axis Tilt is responsible for
The point on earth directly under the sun
Is the latitude of the Subsolar point
The plane on which the earth revolves around the sun
Tilt of the earth from the ecliptic plane (Axial told angle) is
Angles at which the sun hits the Earth
The direction an axis ointment reminds consistent during a yeae
North Pole is pointing
More toward the sun
South Pole is pointing
Further from the sun
Means "equal night" where everyone on earth has 12 hours of darkness on this day. Occurs on March 21 and September 21. Solar declination is zero degrees.
"Solar declination is at 0 degrees" means
The sun is directly overhead at noon on the equator
Solar stand still (reaches as far north or as fall south as it will go)
The northernmost solar declination
Day of greatest insolation in the northern hemisphere
The shortest day for the Southern Hemisphere
Southernmost solar declination
Day of greatest insolation in the northern hemisphere
The shortest day for the Northern Hemisphere
Sun directly overhead at the Tropic of Cancer 23 degrees north.
Tropic of Cancer
Northern most solar declination that occurs on June 21
Tropics are measured at
23. Degrees north or south
Incoming energy varies based on these to factors
the Earth's orientation to the sun and where on Earth it is
At noon on the equinox
Chichen-Itza (1000 AD)
SW corner points to the rising summer solstice sun
NW corner points to the setting winter solstice sun
What determines how much energy reaches the Earth's surface?
Solar angle - beam spreading
Atmospheric beam depletion
Period of daylight
(As a result of the earth's changing orientation to the sun)
Solar angle and beam spreading
Direct vs Oblique
Direct = 2.5x more energy than poles annually
Same amount of energy (that was spread over a small area such as at noon) spreading over a large area (such as during sunset, sunrise, or seasonal low sun angle.)
Daily changes due to rotation
Seasonal changes due to tilt and location in orbit
Beam spreading on June Solstice
Part of earth Dark for 24 hours
Atmospheric Beam Depletion
Different from beam spreading but has the same cause. At higher latitudes, the sun's beams must pass through more of the atmosphere because there is a smaller solar angle. Some incoming energy is reflected or scattered, leaving less to reach the surface.
Variations in Day Length
Latitude affects the amount of energy from insolation. Higher latitudes experience more beam spreading. Lower latitudes experience less beam spreading. Higher latitudes experience more atmospheric beam depletion. Lower latitudes experience less atmospheric beam depletion. At higher latitudes, less energy is received over the course of a year than at lower latitudes.
The sun warms the earth with
shortwave EM radiation
The earth emits
longwave EM radiation
The amount of energy received by the earth depends on
3 Earth-Sun Relationships
The solar energy received at any given location on Earth is dependent on
the time of day, the season, and the latitude of that location.
EMR One wave / cycle per second is measured as
EMR; Adding energy increases
Our eyes see
400 - 700 Hz and help us interpret color via visible light
allows science to study different surfaces of planets
Peak reception occurs at
solar noon when the Sun attains its greatest height above the horizon
Cumulative radiation from the day
the more energy available,
the higher up the Y-axis the profile is on the graph
September equinox is warmer than March equinox because
of the heating that occurred in the previous summer months.
For all dates, minimum temperature occurs at
Daily temperature begins rising when?
as soon as the net radiation budget of the surface becomes positive.
Temperature continues to rise until
sometime after solar noon. After this time, mixing of the Earth's surface by convection causes the surface to cool despite the positive addition of radiation and heat energy.
exactly half the earth is in darkness and half is illuminated.
The earth's axis points toward ____ with a ___ degree tilt.
Polaris with a 23.5 degree tilt.
Sun is shining north of the equator means
it is sometime after march 21 and we are approaching the summer solstice
Solar declination at 23.5 degrees north =
Tropic of Cancer
Variations in net radiation are primarily controlled by
changes in the intensity and duration of received solar insolation which are driven by variations in day length and angle of incidence.
The earth spins on it's axis producing
night and day
An elliptical orbit of the earth around the sun produces
When the Earth's axis points towards the Sun, it is ______ for that hemisphere.
Summer (opposite = winter)
The north pole
Since the tilt of the axis is 23 1/2 degrees, the north pole never points directly at the Sun, but on the summer solstice it points as close as it can, and on the winter solstice as far as it can.
Spring & Autumn
the spin axis of the Earth points 90 degrees away from the Sun. This means that on this date, day and night have about the same length: 12 hours each, more or less.
Why does the tilt of earth's axis matter to our climate?
The density of light drops. In other words, the amount of light per square centimeter drops (the number of square centimeters increases, while the total amount of light stays the same).
Since the Earth's axis is tilted,
the Sun is higher when you are on the part of the Earth where the axis points towards the Sun, and lower on the part of the Earth where the axis points away from the Sun.
For the Northern Hemisphere, the axis points most toward the Sun in June (specifically around June 21), and away from the Sun around December 21. This corresponds to the Winter and Summer Solstice (solstice is Latin for "the sun stands"), or the midpoints of winter and summer. For the Southern Hemisphere, this is reversed.
For both hemispheres, the Earth is 90 degrees away from the sun around March 21 and then again around September 21. This corresponds to the Fall and Spring Equinox (equinox is Latin for "equal night"). Everyplace in the world has about 12 hours of daylight and 12 hours of night.
Because of rotation, the Earth's surface moves at the equator at a speed of about 467 m per second or slightly over 1675 km per hour
The direction of Earth's rotation is
counter-clockwise if viewed from the top / north pole. Opposite from south pole.
One rotation takes exactly _____ and is called a mean solar day
The edge dividing the daylight from night is called the
circle of illumination.
June solstice, September equinox, December solstice, and March equinox.
the angle of the Earth's axis in relation to the ecliptic plane and the North Star on these four dates remains unchanged. Yet, the relative position of the Earth's axis to the Sun does change during this cycle. This circumstance is responsible for the annual changes in the height of the Sun above the horizon. It also causes the seasons, by controlling the intensity and duration of sunlight received by locations on the Earth.
The orbit of the Earth around the Sun is called an _______. This celestial motion takes 365.26 days to complete one cycle.
The ecliptic plane can be defined as
a two-dimensional flat surface that geometrically intersects the Earth's orbital path around the Sun. On this plane, the Earth's axis is not at right angles to this surface, but inclined at an angle of about 23.5° from the perpendicular.
equinox, poles, solstice
During the two equinoxes, the circle of illumination cuts through the North Pole and the South Pole. On the June solstice, the circle of illumination is tangent to the Arctic Circle (66.5° N) and the region above this latitude receives 24 hours of daylight. The Arctic Circle is in 24 hours of darkness during the December solstice.
Earth's seasons are controlled by changes in the duration and intensity of
solar radiation or insolation. Both of these factors are in turn governed by the annual change in the position of the Earth's axis relative to the Sun
angle of incidence
Yearly changes in the position of the Earth's axis cause the location of the Sun to wander 47° across our skies. Changes in the location of the Sun have a direct effect on the intensity of solar radiation. The intensity of solar radiation is largely a function of the angle of incidence, the angle at which the Sun's rays strike the Earth's surface.
Longest days occur during the June solstice for locations ______ of the equator and on the December solstice for locations in the Southern Hemisphere.
north (northern hemisphere)
The equator experiences equal day and night on every day of the year. Day and night is also of equal length for all Earth locations on the September and March equinoxes.
A ball is thrown from the ground with a 45 degree angle between the initial velocity and the horizontal ground. When the ball reaches its highest point above the ground,
The lowest mass that a protostar can have and still become a star (i.e., start thermonuclear reactions in its core) is
If the angular diameter of an observed object can be measured and its distance is known, its true physical diameter can be calculated. True or False?
What is the brightest star in Lyra?
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